Wheel brake for vehicles



Nov. 8, 1927.

J. V. PUGH WHEEL BRAKE vEOE VEHICLES Nov. 8, 192 7. 1,648,864

J. v. PUGH WHEEL BRAKE FOR VEHICLE-s Filed Oct. l5. 1926 3 Sheets-Sheet 2 'FG rfdf rf l Eig. 4

Nov`$ 8, 1927. 1,648,864

J. v. PUGH WHEEL BRAKE FOR VEHICLES mgm.

1 n ven-kr Filed oct. '15. 192e s sheets-slmv s Patented Nov. 8, 1927.

UNITED STATES PATENT OFFICE.

JOHN VERNON PUGH, F COVENTRY, ENGLAND, A SSIGNOR T0 BUDGE-WHITWORTH, LIMITED, OF .COVENTRY, ENGLAND.

WHEEL BRAKE FOR VEHICLES.

Application led October 15, 1926, Serial No. 141,826, and in Great Britain October 13, 1925..

Thisvinvention relates to braking gear for vehicle wheel brakes at the fore and aft or front and rea-r ends of a vehicle, the transmission system -being of the kind having means located somewhere between the region of application of power to the system and the application of gripping forces to the wheels so that the apportionment offeree between the wheels at opposite ends may be m varied in a manner depending upon the total power which is being applied or the distance which has been moved by the pedal or other member at the region where power is in the first instance applied to the system.

The object of the present invention is to provide improved transmission systems adapted to facilitate the apportionment of the gripping forces among the wheels of a vehicle. l

The invention consists in a method of transmitting force from a power application member to ,wheel braking devices at both bends of a vehicle according to which a fluid column, such as the known expedient of a hydraulic piping system, is employed with force-apportioning means as the transmitting agent.

The invention further consists in a method as indicated or apparatus for operating in accordance therewith wherein the member to which power is applied operates pressure plungers connected by independent piping systems to pistons which actuate brake devices at the opposite ends of the vehicle and one of said systems is provided with a variable capacity-resiliently loaded chamber for controlling the gripping force of the brakes at that end of the vehicle.

The invention further consists in a method or apparatus for transmitting force as indicated in which a plunger operated by a pedal or other power application member exerts pressure upon a. piping system connected to pistons which actuate devices at opposite ends of a. vehicle, and means responsive to pressure increase or movement of a plunger, piston or other part are adapted to mitigate or neutralize the force exerted upon the brake-applying elementsl at one end of the vehicle.

The invention further 'consists in a vehicle wheel'brake-applying gear with Huid column actuation means in which a resilient transmitting device Vis inserted between a ance with the invention;

Figure 3 is a detail of a resiliently loaded chamber for one form of the invent-ion; Figures 4 and 5 are details of other forms of variable capacity devices;

Figure 6'is a section on the axis of a single-ended cylinder suitable for applying the brake by means of a torque shaft;

Figure 7 is also a Section on the axis ofla I double-ended cylinder acting on a tension brake of which the ends only are shown;

VFigure 8 is another section on the axis of a double-ended cylinder suitable for applying a tension brake;

Figure 9 is a front view of an expanding brake;

Figure 10 is a view similar to, Figure 6 with a resilient transmission member.

When applying brakes to the wheels at both ends of a vehicle, it is desirable to apportion the gripping force in such a manner that it does not at either end exceed the amount which may be usefully employed in view of the retarding effect that the particular wheels can exert on the vehicle owing to the pressure which they applyto the road surface, and this will depend upon the deceleration which is applied to the vehicle and to the distribution of its total weight among the various wheels and the height of the center of gravity above the wheel base.` Generally speaking the retarding effect of the front Wheels increases when the total power app-lied to the pedal or other force-application member is increased.

In the present application, the invention covers the actuation from the same pedal or foret-application member of two plungers loo with separate piping or lfluid column systems one for the front wheels and one for the back wheels so that the apportionment may be varied by varying the conditions in the two systems. In another application 17 6,149

led March 17, 1927, divided from the present case there is described the use of a common piping or fluid colunm system and means coacting with the fluid-operated pistons to'vary the gripping force at the opposite ends of the vehicle. y

In carrying the invention into edect in the c .a convenlent constructlons shown by way of example in Figures l, 2 and 3, 4 or 5, the

pedal a to which the braking power is applied operates by the shaft a and arms a two pressure plungers a5, a in the cylinders a3, a* of which a3 is connected by a hydraulic pipe system b to the brake devices for the front wheels and a4 is connected by a like system c to the brake devices for the back wheels.

For the front wheels the, fluid column will merely operate pistons which apply the brake devices in any ordinary known way as,for example, as shown in Figure 6, by a piston '07 in a cylinder d moving by means of a strut d2 the freeend of a lever arm di upon a torque shaftalt which applies a brake in any known or convenient way.

The fluid column connection and pistons for the back or non-steering wheels may be of a similar nature but in the system c (Figures l and 2) there is provided a variable capacity resiliently loaded chamber, say in the form of a cylinder e as shown in detail in Figure 3 having a, piston e fitted thereto, which is held at its inward extremity by a coiled spring e2 or alternatively by elastic iluid pressure or other resilient mans.

By the spring e2 or other resilient means any desired initial load may be placed u pon the piston e with the result that Jror light pressure upon the pedal or the like the Nfront brakes and back brakes will be subjected to a similar gripping action 'following a straight line diagram until the fluid pressure is suticient for the capacity of the chamber e in the system c to the back wheels to be increased and 'from this point the gripping torce on the back wheels will. be increased very little, iii at all, while that on the front wheels will geen increasing in substantially the same ratio as before.

l/V hen carrying the invention into en'ect as shown 'in Figures 4 and 5, the variable capacity resiliently loaded chamber may take the :term oi an elastic tube which may be conveniently constructed ot a length oit rubber tube stretched as in Figure 5 over a length of rigid tubing f1 somewhat larger than the internal diameter oil the rubber tube and gripped tightly thereto at each end by the caps f A series ot peritorations f3 are provided in the rigid tube f which are kept closed by the external stressed rubber tubel f until a in the system c connected to the back wheels.

As the rubber tube expands it will present a' continue to increase throughout the range Y of brakeaction.

In Figure 4 a coiled wire f4 is used instead of a perforated tube and in any such devices it is desirable to protect the resilient rubber tube with an external rigid tube or envelope f5 so that expansion beyond a certain point may be prevented.

lnstead of resilient devices such as shown in Figures 3, 4 and 5 for increasing the capacity of the fluid-transmitting column to the back wheels a resilient transmission member such as a coiled spring may be inserted between a piston such as 702 in Figure and an arm such as 706 for applying the back wheel brakes.

lin such a device the cylinder as shown in Figure 10 is provided at the end to which the plpe connection 70 is attached with a piston 712 having suitable cup leather and packing devices and to transmit the movement of the piston 702 to the end ot' the brake lever a shouldered strut 707, 708 is provided, th'd outer and larger diameter end 707 oit which presses upon the end of the lever 706, while the inner and smaller diameter end 708 is provided with a screwed collar 705 at its extremity 'which is` an easy sliding tit in a cavity 70'1 formed in the piston 702. A coiled spring 7c9 surrounds the small end 708 of the strut, abutting its outer end against the shoulder oi the enlarged end 707 and at its inner vend against the collar 705 screwed upon the extremity of the strut. By means of this collar; any desired initial stress may be put upon the spring 709. rllhe inner end of this spring 709' in addition abuts against a step 7010 in the cavity 704 in the piston so that the movement ci' the piston 702 is transmitted tothe end ot' the brake band through the resilient member formed by the coiled spring 709 upon strut 707, 7tlg.

is a modification of the teregoinga single cylinder .may be employed i't'or applying either a tension band to the exterior et a brake drum as in Figures 7 and 8 or ex- `pandible shoes to the interior thereof as in ln. the former case the cylinder may be arranged by means of two movable' pistons, one at each end of the cylinder, Figures 7 and 8, to push apart the ends of two levers Z pivotally mounted at equal distances from the centre ont the brake drum and engaging at their opposite ends the two ends 7 of a. brake band Z2 encircling the same. lin this case the brakes for the fore end wheels will have the pistons o contacting directly with the levers Z connected to the gripping members as shown in Figure 7 while the pistons Z3, Figure 8, for the rear end wheel brakes will be connected to the gripping members through the intermediary of resilient devices Zf. 4

Cylinders as last indicated but without the provision of intermediate levers may be mounted to operate directly between the ends of the two halvesof an internal expanding brake m as shown in Figure 9, the fore end wheel brake cylinders being directly connected as shown in Figure 7 and the rear or aft end Wheel brakecylinders being connected through resilient means such as Zi as before described in connection with Figure 8.

In arrangements operated by a single cylinder as last described, this may be formed as a plain tube n with a pipe connection 'n' at the middle and fitted with an outwardly moving piston Z3 at each end, said pistons pressing either directly or through resilient devices upon .the inner ends of two two-arm levers Z, the outer ends of which are connected to the brake band Z2 in such a manner as to tension the same when the inner ends of the levers Z are pushed out by the pistons. are formed with an eye through which a screwed member Z attached to the end of the brake band Z2 projects and are provided with nuts Z for tightening the same. These nuts Z6 of the screwed members Z which are directed towards one another are each provided with a coiled spring Z" and. the two springs find their abutments upon the arms of a central fixed element Z8, one pressing upon one side and the other upon the other side. These springs are for the purpose of releasing the brake.

Having now described my invention what I claim as new and desire to secure by Let- 1. A vehicle wheel brake-applyingl gear having in combination cylinders a-ving -'Huid-displacing means, means for actuating the same braking devices for wheels at the back and those at the front of the vehicle, a Huid-operated piston actuating a front wheel braking device, a piston actuating a like device for a back Wheel, independent lfluid transmission means connecting said .fluidisplacin means, means for actuating the same braking devices for wheels at the front and'for those at-the back of the vehicle, a Huid-operated piston actuating the The outer ends of the levers1 front wheel braking device, a piston actuating the device for a back wheel, a separate 3. A system of hydraulic brake control comprising Wheel braking devices at the front 'and at the rear of a vehicle, pressure cylinders with pistons for operating each device, a separate fluid column transmission to each cyl1nder, cylinders with means for applying pressure to each fluid column, means for jointly operating said vplungers and resilient means in the part of the system for the back wheels which deflects at some predetermined pressure so that 'thereafter the proportion of the total force available for applying all the brakes which is exerted on the braking devices at the front exceeds that exerted on those at' the back.

4. A system of hydraulic brake control comprising wheel braking devices at the front and at the rear of a vehicle, fluidmved members for operating the same, separate pipe runs to each member, fluid-displacing means connected to each pipe run, Y

means, and resilient means acting after a predetermined pressure is reached to apportion the greatest share of the total force exerted for applying all the brakes to the front wheel braking devices during continued brake application.

5. A system of hydraulic brake control comprising Huid-operated wheel braking devicesat the front of a vehicle, similarly op'- erated devices at the rear thereof, a separate fluid column transmission to each device, means for applying pressure to each iiuid column, means for jointly operating said pressure-applying means and resilient means in the part of the system for the back wheels which deflects at some predetermined ressure so that thereafter the proportion o the total forceavailable for applying all the v brakes which is exerted on the braking devices at the front exceeds that exerted on those at the back.

6. A system of hydraulic brake control comprising fluid-operated wheel brakin devices at the front of a vehicle, simi arly operated devices at the rear thereof, separate pipe runs to each of said devices, means for creating fluid pressure in` each of said pipe runs, means forjointly operating said pressure-creating means, and lmeans acting at a predetermined pressure to increase the capacity ofthe pipe run to the back w'heels and thus limit the pressure therein during continued brake app ication.

7. A vehicle Wheel brake-applying gear havin in combination Vcylinders `having fiuidisplacing means, means for actuating the same, a fluid-operated piston for actuating a front wheel braking device, a piston for actuating a like device for a back Wheel, independent fluid column systems connecting said plungers with said pistons, and a resilient capacity-increasing device in the system to the piston operating the braking device for the back Wheel.

8. A- vehicle wheel brake-'applying gear having i'n combination cylinders having fluid-displacing means, means for actuating the same,a fluid-operated piston for actuating a front Wheel braking device, a piston for actuating a like device for a back Wheel, independent Huid column systems connecting said plungers with said istons, and a chamber extensible by a pre etermined pressure connected to the system for the piston operating the braking device for the back wheel.

9. A vehicle Wheel brake-applyin gear having in combination cylinders aving luid-displacin means, means for actuating the same, a fluid-operated piston for actuating a front Wheel braking device, a piston for actuating a like device for a back Wheel, independent iiuid column systems connectin said plungers with said pistons, and a cy indrical chamber having a resiliently loaded piston fitted thereto connected to the system for the iston operating the braking device for the ack Wheel.

10. A system of hydraulic brake control comprising Wheel braking devices at the lfront and at the rear of a vehicle, iiuidmoved members for operating the same, separate pipe runs to each member, fluiddisplacing means connected to each pipe run, means for jointly operating said displacing means, and a chamber extensible by a predetermined pressure connected to the pipe run for the member operating the rear Wheel braking devices.

11. A system of hydraulic brake control comprising' Wheel braking devices at the front and at the rear of a vehicle, fluidmoved members for operating the same, separate pipe runs to each member, fluiddisplacing means connected to each pipe run, means for jointly operating said displacing means, and a cylindrical chamber having 'a resiliently loaded piston fitted thereto connected to the pipe run for the member operating the rear wheel braking devices.' y

12. A vehicle wheel brake-applying gear having in combination two cylinders having fluid-displacing means, a pedal actuating the same, brake-applying devices for Wheels p at the front and for those at the back of the vehicle, a fluid-operated piston actuating adisplacin means operated thereb independent draulic piping systems connecting said cylinders to actuating pistons, brake-applying devices for the Wheels at opposite endsV of the vehicle and variable capacity resiliently loaded chamber means provided in the plping to the back end for iminishing the proportion ofthe total force exertedfor applying all the brakes which istransmitted to the brakes at that end of the vehicle.

14. A system of hydraulic brake control, comprising friction brake gripping devices at the front and at the' rear of a vehicle,

fluid-moved members for operating the p same, separate pipe runs to each member, fluid-displacing means connected to each pipe run, means for jointly operating said displacing means and deflectable resilient means co-operating With a rear Wheel brake device to maintain Within a predetermined J pressure the force transmitted to said rear brake device by its pipe run.l

In testimony whereof I have signed my name to this specification.

JOHN VERNON PUGH. 

